| Symbol | Scientific name | Common name/Accepted name (for synonyms) | Family |
| ASSE13 | Astragalus sealei Lepage | Astragalus eucosmus | Fabaceae
|
| ASSE3 | Astragalus sepultipes (Barneby) Barneby | Lone Pine milkvetch | Fabaceae
|
| ASSES3 | Astragalus serenoi (Kuntze) Sheldon var. serenoi | naked milkvetch | Fabaceae
|
| ASSES4 | Astragalus serenoi (Kuntze) Sheldon var. shockleyi (M.E. Jones) Barneby | Shockley's milkvetch | Fabaceae
|
| ASSES | Astragalus serenoi (Kuntze) Sheldon var. sordescens Barneby | naked milkvetch | Fabaceae
|
| ASSE4 | Astragalus serenoi (Kuntze) Sheldon | naked milkvetch | Fabaceae
|
| ASSE15 | Astragalus sericea auct. non DC. | Astragalus sericoleucus | Fabaceae
|
| ASSEA | Astragalus sericoleucus Gray var. aretioides M.E. Jones | Astragalus aretioides | Fabaceae
|
| ASSET | Astragalus sericoleucus Gray var. tridactylicus (Gray) M.E. Jones | Astragalus tridactylicus | Fabaceae
|
| ASSE5 | Astragalus sericoleucus Gray | silky milkvetch | Fabaceae
|
| ASSE14 | Astragalus serotinus Gray ex Cooper | Astragalus miser var. serotinus | Fabaceae
|
| ASSE6 | Astragalus serpens M.E. Jones | plateau milkvetch | Fabaceae
|
| ASSEB | Astragalus sesquiflorus S. Wats. var. brevipes Barneby | Astragalus sesquiflorus | Fabaceae
|
| ASSE7 | Astragalus sesquiflorus S. Wats. | sandstone milkvetch | Fabaceae
|
| ASSH2 | Astragalus sheldonii (Rydb.) Barneby | Sheldon's milkvetch | Fabaceae
|
| ASSH5 | Astragalus shevockii Barneby | Little Kern milkvetch | Fabaceae
|
| ASSH8 | Astragalus shockleyi M.E. Jones | Astragalus serenoi var. shockleyi | Fabaceae
|
| ASSH3 | Astragalus shortianus Nutt. | Short's milkvetch | Fabaceae
|
| ASSH7 | Astragalus shultziorum Barneby | Astragalus molybdenus | Fabaceae
|
| ASSIC | Astragalus silerianus M.E. Jones var. cariacus M.E. Jones | Astragalus subcinereus | Fabaceae
|
| ASSI11 | Astragalus silerianus M.E. Jones | Astragalus subcinereus | Fabaceae
|
| ASSI3 | Astragalus siliceus Barneby | Flint Mountain milkvetch | Fabaceae
|
| ASSI4 | Astragalus simplicifolius (Nutt.) Gray | little bun milkvetch | Fabaceae
|
| ASSI5 | Astragalus sinuatus Piper | Whited's milkvetch | Fabaceae
|
| ASSO3 | Astragalus solitarius M.E. Peck | solitary milkvetch | Fabaceae
|
| ASSO4 | Astragalus sophoroides M.E. Jones | painted desert milkvetch | Fabaceae
|
| ASSO5 | Astragalus soxmaniorum Lundell | Soxman's milkvetch | Fabaceae
|
| ASSPT | Astragalus spaldingii Gray var. tyghensis (M.E. Peck) C.L. Hitchc. | Astragalus tyghensis | Fabaceae
|
| ASSP4 | Astragalus spaldingii Gray | Spalding's milkvetch | Fabaceae
|
| ASSPM | Astragalus sparsiflorus Gray var. majusculus Gray | Front Range milkvetch | Fabaceae
|
| ASSPS3 | Astragalus sparsiflorus Gray var. sparsiflorus | Front Range milkvetch | Fabaceae
|
| ASSP5 | Astragalus sparsiflorus Gray | Front Range milkvetch | Fabaceae
|
| ASSPU | Astragalus spatulatus Sheldon var. uniflorus (Rydb.) Barneby | Astragalus spatulatus | Fabaceae
|
| ASSP6 | Astragalus spatulatus Sheldon | tufted milkvetch | Fabaceae
|
| ASSP7 | Astragalus speirocarpus Gray | threadstalk milkvetch | Fabaceae
|
| ASSP15 | Astragalus splendens (Dougl. ex Hook.) Tidestrom | Oxytropis splendens | Fabaceae
|
| ASSTF | Astragalus stenophyllus Torr. & Gray var. filipes (Torr. ex Gray) Tidestrom | Astragalus filipes | Fabaceae
|
| ASST9 | Astragalus stenophyllus Torr. & Gray | Astragalus filipes | Fabaceae
|
| ASST4 | Astragalus sterilis Barneby | Astragalus cusickii var. sterilis | Fabaceae
|
| ASST12 | Astragalus stictocarpus (Rydb.) Tidestrom | Astragalus flexuosus var. greenei | Fabaceae
|
| ASST8 | Astragalus stocksii Welsh, non Benth. ex Bunge | Astragalus argophyllus var. stocksii | Fabaceae
|
| ASST11 | Astragalus stragulus Fern. | Astragalus bodinii | Fabaceae
|
| ASST5 | Astragalus straturensis M.E. Jones | Pine Valley milkvetch | Fabaceae
|
| ASST6 | Astragalus striatiflorus M.E. Jones | escarpment milkvetch | Fabaceae
|
| ASST82 | Astragalus striatus Nutt. | Astragalus laxmannii var. robustior | Fabaceae
|
| ASST10 | Astragalus strigosus Coult. & Fisher | Astragalus miser var. miser | Fabaceae
|
| ASSUB | Astragalus subcinereus Gray var. basalticus Welsh | Astragalus subcinereus | Fabaceae
|
| ASSU6 | Astragalus subcinereus Gray | Silver's milkvetch | Fabaceae
|
| ASSU13 | Astragalus subglaber (Rydb.) M.E. Peck | Astragalus curvicarpus var. subglaber | Fabaceae
|
| ASSU8 | Astragalus subvestitus (Jepson) Barneby | Kern County milkvetch | Fabaceae
|
| ASSU12 | Astragalus succulentus Richards. | Astragalus crassicarpus var. crassicarpus | Fabaceae
|
| ASSU7 | Astragalus succumbens Dougl. ex Hook. | Columbia milkvetch | Fabaceae
|
| ASSU11 | Astragalus sulphurescens Rydb. | Astragalus laxmannii var. robustior | Fabaceae
|
| ASTE4 | Astragalus tegetarioides M.E. Jones | bastard milkvetch | Fabaceae
|
| ASTE14 | Astragalus tegetarius S. Wats. | Astragalus kentrophyta var. tegetarius | Fabaceae
|
| ASTE15 | Astragalus tehatchapiensis (Rydb.) Tidestrom | Astragalus lentiginosus var. idriensis | Fabaceae
|
| ASTES | Astragalus tenellus Pursh var. strigulosus (Rydb.) F.J. Herm. | Astragalus tenellus | Fabaceae
|
| ASTE5 | Astragalus tenellus Pursh | looseflower milkvetch | Fabaceae
|
| ASTEF | Astragalus tener Gray var. ferrisiae A. Liston | Ferris' milkvetch | Fabaceae
|
| ASTET2 | Astragalus tener Gray var. tener | alkali milkvetch | Fabaceae
|
| ASTET | Astragalus tener Gray var. titi (Eastw.) Barneby | coastal dunes milkvetch | Fabaceae
|
| ASTE6 | Astragalus tener Gray | alkali milkvetch | Fabaceae
|
| ASTE7 | Astragalus tennesseensis Gray ex Chapman | Tennessee milkvetch | Fabaceae
|
| ASTEB | Astragalus tephrodes Gray var. brachylobus (Gray) Barneby | ashen milkvetch | Fabaceae
|
| ASTEC | Astragalus tephrodes Gray var. chloridae (M.E. Jones) Barneby | ashen milkvetch | Fabaceae
|
| ASTEE | Astragalus tephrodes Gray var. eurylobus Barneby | Astragalus eurylobus | Fabaceae
|
| ASTER2 | Astragalus tephrodes Gray var. remulcus (Gray) Barneby | ashen milkvetch | Fabaceae
|
| ASTET3 | Astragalus tephrodes Gray var. tephrodes | ashen milkvetch | Fabaceae
|
| ASTET4 | Astragalus tephrodes Gray var. typicus Barneby | Astragalus tephrodes var. tephrodes | Fabaceae
|
| ASTE8 | Astragalus tephrodes Gray | ashen milkvetch | Fabaceae
|
| ASTE9 | Astragalus terminalis S. Wats. | railhead milkvetch | Fabaceae
|
| ASTEC2 | Astragalus tetrapterus Gray var. capricornus M.E. Jones | Astragalus tetrapterus | Fabaceae
|
| ASTEC3 | Astragalus tetrapterus Gray var. cinerascens (Rydb.) Barneby | Astragalus tetrapterus | Fabaceae
|
| ASTE10 | Astragalus tetrapterus Gray | fourwing milkvetch | Fabaceae
|
| ASTH2 | Astragalus thompsoniae S. Wats. | Astragalus mollissimus var. thompsoniae | Fabaceae
|
| ASTH | Astragalus thurberi Gray | Thurber's milkvetch | Fabaceae
|
| ASTI5 | Astragalus tibetanus Benth. ex Bunge | Tibet milkvetch | Fabaceae
|
| ASTI | Astragalus tidestromii (Rydb.) Clokey | Tidestrom's milkvetch | Fabaceae
|
| ASTI3 | Astragalus tiehmii Barneby | Tiehm's milkvetch | Fabaceae
|
| ASTI2 | Astragalus titanophilus Barneby | limestone milkvetch | Fabaceae
|
| ASTOS | Astragalus toanus M.E. Jones var. scidulus Welsh & Atwood | Toano milkvetch | Fabaceae
|
| ASTOT | Astragalus toanus M.E. Jones var. toanus | Toano milkvetch | Fabaceae
|
| ASTO2 | Astragalus toanus M.E. Jones | Toano milkvetch | Fabaceae
|
| ASTO3 | Astragalus toquimanus Barneby | Toquima milkvetch | Fabaceae
|
| ASTO9 | Astragalus tortipes J.L. Anderson & J.M. Porter | sleeping Ute milkvetch | Fabaceae
|
| ASTR4 | Astragalus traskiae Eastw. | Trask's milkvetch | Fabaceae
|
| ASTR5 | Astragalus tricarinatus Gray | triplerib milkvetch | Fabaceae
|
| ASTR18 | Astragalus trichocalyx Nutt. | Astragalus crassicarpus var. trichocalyx | Fabaceae
|
| ASTRA3 | Astragalus trichopodus (Nutt.) Gray ssp. antisellii (Gray ex Brewer & S. Wats.) Thorne | Astragalus trichopodus var. phoxus | Fabaceae
|
| ASTRL2 | Astragalus trichopodus (Nutt.) Gray ssp. leucopsis (Torr. & Gray) Thorne | Astragalus trichopodus var. lonchus | Fabaceae
|
| ASTRC | Astragalus trichopodus (Nutt.) Gray var. capillipes (M.E. Jones) M.E. Jones | Astragalus trichopodus var. trichopodus | Fabaceae
|
| ASTRL | Astragalus trichopodus (Nutt.) Gray var. lonchus (M.E. Jones) Barneby | Santa Barbara milkvetch | Fabaceae
|
| ASTRP | Astragalus trichopodus (Nutt.) Gray var. phoxus (M.E. Jones) Barneby | Santa Barbara milkvetch | Fabaceae
|
| ASTRT2 | Astragalus trichopodus (Nutt.) Gray var. trichopodus | Santa Barbara milkvetch | Fabaceae
|
| ASTR6 | Astragalus trichopodus (Nutt.) Gray | Santa Barbara milkvetch | Fabaceae
|
| ASTR7 | Astragalus tridactylicus Gray | foothill milkvetch | Fabaceae
|
| ASTR12 | Astragalus triphyllus Pursh | Astragalus gilviflorus var. gilviflorus | Fabaceae
|
| ASTR19 | Astragalus triquetrus Gray | Astragalus geyeri var. triquetrus | Fabaceae
|
| ASTR8 | Astragalus troglodytus S. Wats. | creeping milkvetch | Fabaceae
|
| ASTW | Astragalus tweedyi Canby | Tweedy's milkvetch | Fabaceae
|
| ASTY | Astragalus tyghensis M.E. Peck | Tygh Valley milkvetch | Fabaceae
|